Bioaccumulation of heavy metals in silver catfish (Chrysichthys nigrodigitatus) and tilapia fish (Oreochromis niloticus) from the brackish and freshwater in South-West, Nigeria

Abstract

BackgroundChrysichthys nigrodigitatus (CN) and Oreochromis niloticus (ON) health status were investigated in Asejire Reservoir (AR) and Lagos Lagoon (LL), South-west Nigeria. Fish samples collected were separated into sexes. Growth pattern {length (cm); weight (g), Isometric index, condition factor (K)} were measured. Heavy metals (lead (Pb), iron (Fe), zinc (Zn), copper (Cu), and chromium (Cr) in ppm concentrations were determined in Lagos Lagoon and Asejire reservoir.ResultsFish samples ranged at one male to one or two females. No significant difference in length and weight of O. niloticus between locations. Significant difference in weight occurred in C. nigrodigitatus between locations; highest condition factor was recorded in Asejire Reservoir O. niloticus, (ARON); lowest condition factor was observed in Asejire Reservoir C. nigrodigitatus (ARCN) as this indicated a negative allometric value, normal in Bagridae species. Male species possessed higher condition (K)—factor than female species within locations, between locations, between species, and within species, female C. nigrodigitatus having higher condition factor than male ARCN. Highest isometric value occurred in ARON and lowest in Lagos Lagoon C. nigrodigitatus (LLCN). Male ARON had highest isometric value, and O. niloticus species had higher isometric value (b ≤ 3) and positive allometric (b > 3); and C. nigrodigitatus has negative allometric (b < 3). Heavy metals Zn had highest value, while Cr ranked lowest value for ARON. Lagos Lagoon O. niloticus (LLON) Zn had highest value while Pb had lowest value. LLCN heavy metals determined revealed Zn had highest value, while Cr had lowest value; and ARCN heavy metals determined revealed Zn had highest value, and Cr had lowest. In all, Zinc (Zn) was top-ranked.ConclusionResults indicate niche response and performance as species specific; while environmental influence and stressors, food availability and reproduction factors contribute to well-being of fish. The heavy metals influence on the fish species is of public concern to man to avoid food poisoning.